[boo5790]

hey all, my neighbour is having a wierd problem. when he has his computer on a few of his cable channels have lines running through them. when he shuts off the computer, the channels are clear as day. i was wondering if anyone has any thoughts as to what in his computer might be causng the interference. it is only a few channels not all of them. he is running windows xp

[cwwozniak]

Does the cable connect to the computer in any way (Cable modem or tuner card in the computer)?

Is the computer connected directly to the TV?

Have any case mods been done to the computer (CFL lighting, clear window, etc.)

Does the interference still appear if all external hardware (mouse, keyboard, monitor, speakers, external drive, printer, etc.) is unplugged from the computer?

Does the computer have any kind of wireless hardware installed?

Does the amount of interference depend on the distance of the computer from the TV or the cable tuner box?

[boo5790]

hi cwwozniak, the cable does not connect to the tv

the computer is not connected to the tv

no case mods have been done

the interference still appears when all external hardware is unplugged

the distance the computer is from the tv has no effect.

tonight we unhooked his tower and hooked up his wifes tower with all the same cables and external hardware and there was no interference whatsoever. so the problem is something inside his tower it seems. all was okay and the problem started about a month ago. i dont know if he took it in to a tech if they have a way to find out what the problem is

[cwwozniak]

Thank you for running the checks and eliminating some of the easy stuff that might be the cause.

Trying to find the source of the interference may require some equipment that may not be found in a typical computer repair shop. If they can somehow duplicate the problem on a TV in the shop, they might be able to try replacing things like the power supply, motherboard, and video controller card and see if the problem disappears.

Since you say that distance does not affect the severity of the problem, I would tend to suspect the interference may be coming through the AC power lines. I am not familiar with PC supplies to know if there is anything that can fail so that the supply seems to run normally but could be dumping noise into the AC input

[JohnWill]

I'd start at electrical grounding for the case. I'd also put an EMI filter on the power connection, just to eliminate that possibility. This kind of issue is most frequently an issue within the power supply, high frequency interference would normally happen much closer to the machine.

[boo5790]

hi JohnWill, i will pass on your reccomendations and post back when he has the problem resolved